Closing the Emplacement Chambers of the Konrad Repository

In Germany, non-heat-generating, #radioactivewaste is to be disposed of in the #Konrad repository. The waste packages are to be stacked in emplacement chambers that are up to approx. 1 km long. The packages will be placed in sections of 50 m length. Then, #shotcrete will be applied to the last stack of packages, thus creating a wall that allows backfilling of the section with a high-flowable #mortar. At the entrance to the emplacement chambers, there are areas for reloading packages and for turning vehicles. Large ventilation boreholes open into these areas. These areas and boreholes are also to be backfilled.

At the chamber entrances, however, it is not possible to apply shotcrete to waste packages. The task was therefore to compile options for a support and to evaluate the technical feasibility of its construction in the controlled area of the repository and to assess whether the construction can be integrated into the work processes. The support materials must not be combustible and must be transportable underground and to the place of use in sufficient amounts. It must be possible to erect the support in a short time, with little effort, and with existing equipment. After shotcrete has been applied, all walls must meet the static requirements and be solution-tight.

For example, empty containers (dummy containers), formwork blocks, mobile formwork systems, and the creation of walls with flexible plastic tubes were considered. The options were evaluated by BGE TECHNOLOGY GmbH based on a specially developed evaluation matrix with weighted factors. In this context, our extensive practical experience gained in the context of backfilling and sealing measures was of great benefit. In the end, reference solutions were selected in cooperation with mining engineers from the site. This way, another cornerstone was laid for the smooth execution of the emplacement operations in the Konrad repository.